ABSTRACT

To reproduce an object means that the structure of one object constrains the structure of another; the original imposes boundary conditions on the duplicate. For simple objects this appears straightforward, but for complex systems less so. Since sequences are easy to reproduce, the living world replicates by copying the DNA sequence and using the copy to construct a second organism. John von Neumann formalized this process in his prescient Theory of Self-Reproducing Automata (TSRA), which extended principles of the Turing Machine into the physical world. The TSRA correctly anticipated much of the way the cell actually works. Von Neumann logically separated the construction and copying functions, not as a matter of convenience, but as a matter of necessity. This underlies the genotype-phenotype distinction, which Francis Crick explored in his Central Dogma. Sequences are either replicated as rate-independent patterns or expressed as rate-dependent interactors, but not both by the same mechanism. A text has a physical structure that is independent of its interpretation. A teacher configures a five-year-old to perform two independent activities: interpreting and replicating texts. To interpret means to read the text for meaning. To replicate means to copy only its physical structure, without regard to meaning.